Carburetor



R. F. BRACKE I CARBURETOR l Filed April 8, 1926 29, 1931. RF. BRACKE v 1%8387902 CARBURETOR Filed April 8, 1926 2 Sheets-Sheet 2 Patented Dec. 29, 1931 UNITED STATES PATENT OFFICE t,

ROBERT F. BRACKE, OF CHICAGO, ILLINOIS, ASSIGNOR TO WILLIAMS, CAMP AND BRAD- BURY, A COPARTNERSHIP COMPOSED OF LYNN A. WILLIAMS, CURTIS 1B. CAMP, ANI) CLIFFORD C. IBRADBURY, OF CHICAGO, ILLINOIS CARBURETOR I Application led April 8, 1926. Serial N'o. 100,516.

My invention relates to vacuum feed or self feed carburetors and more particularly to that type in which a suction controlled diaphragm or other movable partition regulates the depression in the chamber from which the nozzle is supplied.

My invention includes several features of novelty pertaining particularly to carburetors in which the fuel chamber, located at the from fuel.

carburetor, is under depression below atmosphere and in fact below that of the carburetor mixing chamber.

One feature of my invention is the construction of the carburetor air intake valve and the means for lubricating it. vIt has been foundythat an air dashpot to function the. same at all times should be kept free If fuel is allowed to wet the surface of the piston, it will sometimes form a seal between the piston and its cylinder and sometimes not, with the result that the dashpot will vary in its effectiveness. To avoid this, I provide an actual clearance be,- tween the piston and its cylinder and guide the piston by its stem which is lubricated by fuel in a novel manner.,

Another feature of my invention is the provision of a so-called economizer so arranged as to make lean the mixture of fuel and air at that position of the throttle` at which the engine is run in maintaining the vehicle in which it is mounted at a constant speed of twenty-ve to thirty-five miles per hour on level roads.

Another feature of my invention has to do with the construction of the diaphragm and the valve controlled thereby, whereby uniform operation is Secured.

Other features `of my invention will be more fully pointed out in the following specification and claims, reference being made to the accompanying drawings in which like characters represent the same parts throughout the several views and in which Figure 1 is an elevation of a detached carburetor;

Figure 2 is a top View;

Figure 3 is a section taken on the line 3-3 of Figure 2; f

Figure 4 is a section through the economizer mechanism and nozzle taken on line 4-4 of Figure 1; and

Figure 5 shows the carburetor mounted on an automobile chassis and connected to a low level source of fuel supply.

Referring to the drawings, the flanged casing 7 with the throttle 8 and the body 9 enclose and form the induction passage.

The main air intake 10 is provided with a choke throttle 11 suitably connected to the operators position by means not shown. A valve 12 forms a variable restriction to the How of air to the mixing chamber 14, thus at all times during engine operation creating a suction in the mixing chamber which, as will be hereinafter described, may be augmented for lifting fuel from the low level supply tank 15 (Fig. 5).

The valve 12 is connected with a stem 16 by means of a hollow screw 17, there being lateral holes 18 extending to the surface of the stem by which liquid fuel passes to lubricate thev surface between the stem 16 and its guide 20.

The lower end of the stem 16 carries a piston 21 operating within a cylinder 22 formed in the body 9. It has been found preferable that this piston 21 be made of such size that its periphery is actually spaced from the cylinder 22 by several thousandths of an inch, the'stem 16 and guide 20 serving to hold the piston centrally within the cylinder. The function of the piston and cylinder is to retard the movement of the valve 12 so as to provide a short period of high mixin chamber suction when the throttle 8 is opened, wherebyl the mixture proportions of fuel and air will be maintained during engine acceleration. The degree of retardation caused by the piston may be governed i by the size of the hole 23 which penetrates its base.- This hole also acts as an outlet for such liquid fuel as passes down along the stem 16 and in conjunction with the vent 24 discharges such liquid fuel Without its com- 95 ing into contact with the Walls of the cylinder 22. This is important as it prevents fluctuations in the degree of retardation caused by the piston. Y

The valve 12 is urged toward its seat by a fixed spring 26 surrounding the stem 16 and is urged from its seat by a less effective adjustable spring 27 mounted within the stem 16, and is preferably guided by the column 28 carried upon the adjusting screw 29. It

has been found advantageous to shield the tube is so small as to admit less air than is required for running the engine at its lowest idling speed, the remainder being drawn past the valve 12 which even at idling islifted slightly of its seat. The action of the air rushing through the Venturi tube 32 creates a suction on the fuel ports 35 which is sev eral times as great as that of the 'mixing chamber, and which acts to lift the fuel from the low level source of supply as well as deliver it into the mixing chamber. Fuel reaches the annular passage 37, with which the ports 35 connect, through a duct 38 drilled through a portion of the casing 9 to the fuel chamber 40 in which the fuel is maintained under a substantially constant depression by the action of a valve 41y interposed in the fuel passage between the low-level source of fuel supply and the fuel chamber 40. This .valve is normally held against its seat 42 by a spring 43 and is adapted to be pushed from its seat by the diaphragm 45 when the suction beneath the diaphragm reaches a predetermined amount just suilicient to overcome the pressure of the spring 46 acting directly on the diaphragm and that of the spring 43 acting on the valve 41. By this construction the height of the fuel lift or even the matterof whether the fuel is fed to the valve by suction orJ under pressure has only very slight effect upon the degree of depression in the fuel chamber 40 so long as the suction required to lift fuel from the low level source to the valve 41 is less than the suction in the fuel chamber 40.

In the present construction the valve 41 is acted upon by four f`rces,the spring 43 tending to hold it closed, suction in the chamber 40ftending to pull it closed, the diaphragm 45 tending-to push it open,and the suction or pressure of the fuel column tend'- ing to pull it open or push it closed as the case may be. These forces must under all conditions strike a balance at which the valve 41 will stand at rest. If it be assumed that the suction in the chamber 40 remains constant at a time when the column of fuel changes from negative pressure (suction) to positive pressure (gravity iow) ,Non the valve 41, then the change in pressure on the valve due to this change in fuel head must be met by other forces than that of suction on the diaphragm. i

Means are provided for controlling the amount of air supplied to the Venturi tube 32 in accordance with the position of the throttle, for the purpose of making the mixture more lean when the throttle is positioned so that the automobile on which the carburetor is mounted will travel at a speed of about thirty-live miles an hour ona level road. This economizer comprises a valve body 51, which fits over the outer end of the Venturi tube 32, and may be secured thereto by a suitable set screw 52. A valve 53, integral with its stern 54, lis mounted for vertical reciprocation in the body 51, being resiliently urged upwardly by the coil spring 55, one end of which has a bearin at the lower end of a cylindrical bore 56 in t e body 51 and theother end of which bears against a collar 57 secured to, or integral with the stem 54. A knurled, threaded sleeve 58 which is screwed into the upper end 0f the body, has a plurality of apertures 59 through which air may pass from the surroundmg atmosphere to the main chamber 61 of the valve. An inwardly projecting ring 62, integral with the sleeve 58, is a means for partially restricting the flow of air to the Venturi tube when the valve 53 is depressed so that it lies near or in the plane of this annular ring. The sleeve 58 may be readily adjusted by rotating it in the body51 and may be secured in adjusted position by a set screw 63. The valve is actuated by an arm 64 which is integral with the throttle arm 65 which, as is usual, is secured to the pivotally mounted throttle stem 66. It will be apparent that when the throttle 1s opened to a predetermined position, the arm 64`wi1l engage the stem 54 of the valve 53 and depress the valve suiiciently tomaterially restrict the passage of air into the chamber 61 and the flow of air through the Venturi tube 32 will thereby be limited and as a' consequence a smaller proportion of fuel Will be drawn into the induction passage 14. A plurality of Calibrating plugs 33, having bores of various diameters are provided to permit more or less permanent adjustment of the supply of air to the Venturi tube 32, while the valve 53 provides for the regulation of the quantity of air passing to the Venturi tube at predetermined positions of the throttle. By adjusting the position of the sleeve 58, the valve may be conditioned so as to be operable at the desired position of the throttle. f

While the form of mechanism herein shown Aand described is admirably adapted to fulfill the objects stated, it is to be understood that it is not intended to confine the invention to the one form of embodiment herein disclosed, for it is susceptible of embodiment in various forms, all coming within the scope of the claims which follow:

I claim:

1. In a carburetor, the combination of a body having an induction passage, a throttle valve pivotally mounted in said body, a Venturi tube for supplying a mixture of4 fuel and air to said induction passage, air admitting means to admit a predetermined amount of air to said venturi, additional means for regulating the quantity of air to said Venturi tube comprising a valve body secured to said tube, a valve reciprocable in said body, means for controlling the position o-fsaid valve in accordance with the position of said throttle, and means for adjusting said valve to make it operable at selected positions of said throttle.

2. In a carburetor, the combination of a body having an induction passage therein, a throttle valve pivotally mounted in said assage, means for actuating said valve, a enturi tube for supplying a mixture of fuel and air to said passage, means to admit a predetermined amount of air to said Venturi tube, and additional means for regulating the amount of air admitted to said Venturi tube, said last named means being operated by said throttle valve actuating means at predetermined throttle positions.

3. In a carburetor, the combination of a body having an induction passage thereln, a throttle valve pivotally mounted in said passage, means for actuating said valve, a Nenturi tube for supplying a mixture of fuel and air to said passage, means to admit a predetermined amount of air to said Venturil tube, additional means for regulating ythe amount of air admitted to said Venturi tube, said last named means being operated by said throttle actuating means, and means for adjusting said additional regulating means to be operable at predetermined positions of said throttle.

4. In a fuel lift carburetor, the combination of an induction passage having a main air inlet, a throttle valve in said passage, a Venturi tube forming a prinary air inlet projecting within said passage and having its throat connected to a low level fuel Supply, a-

valve body surrounding the air inlet orifice of the venturi, said body having a part apertured to permit a predetermined amount of air from' the atmosphere to pass therein, and a valve for said body communicatingwith the atmosphere and operated by said throttle for regulating an additional flow of air to the valve body, said valve being adjustable to maintain its greatest restriction at a desired position of the throttle valve.

5. In a fuel lift carburetor, the combination of an induction passage having a main air inlet, a throttle valve in said passage, a Venturi tube forming a primary air inlet projecting within said passage anterior to said throttle valve and having its throat connected to a low level fuel supply, a valve body surrounding the air inlet orifice of the venturi, said body having a part apertured to permit a predetermined amount of air from the atmosphere to pass therein, and a valve for said body communicating with the atmosphere and operated by said throttle for regulatin an additional iow of air to the valve bo y, said valve being adjustable to maintain its greatest restriction at a desired position of the throttle'valve. f

6. A carburetor comprising in combination an induction passage, a throttle valve in said passage, a Venturi tube forming a communication between the atmosphere and said passage for supplying a mixture of fuel and air to the induction passage, a valve body secured to said tube and means therein for supplying a predetermined amount of air thereto, an adjustable valve reciprocal in said body and controlling an additional ioW of air supplied to said venturi, means controlling the position of said valve in accordance with the position of said throttle, and means for adjusting said valve to operate at selected positions of said throttle whereby to regulate the amount of air admitted to sald venturi.

7. A fuel lift carburetor comprising in combination an induction passage, a Venturi tube having an end exposed to the atmosphere and projecting into said passage for supplying a mixture of fuel and air thereto, means for admitting a predetermined amount of air to said venturi means for supplying fuel to the throat of said venturi, a throttle valve in said passage posterior to said venturi, means controlling the position of said throttle and other means operable by the throttle control means controlling additional air admitting means for diminishing the amount of air received by the Venturi end exposed to the atmosphere whereby the quantity of fuel conveyed through said venturi is diminished at a desired throttle position.

. 8. A fuel lift carburetor comprising in combination a body having an induction passage, a Venturi tube transversely disposed in said passage and having an end exposed to the atmosphere, said Venturi tube projecting into the induction passage for supplying a mixture of fuel and air to said passage, means for supplying fuel to the throat of said venturi, a throttle valve in said passage, throttle operating means for actuating said throttle anda valve operable by said throttle operating means to reduce the amount of air admitted to said venturi at a predetermined throttle position whereby to reduce the quantity of fuel conveyed through the said venturi.

9. A fuel lift carburetor comprising in combination an induction passage having an air inlet, a Venturi tube projecting transversely of and within said passage and forming a primary air inlet for supplying air to said passage and for maintaining a relatively constant depression therein, a .source of fuel supply communicating with the throat of said venturi, a throttle valve pivotally mounted in said passage posterior to said Venturi tube, a valve controlling the admission of air to said Venturi tube, and throttle operating means for controlling the position of said Valvey in accordance with the position of said throttle Whereby'to supply a desired mixture of air and fuel to said induction passa e.

n Witness whereof, I. hereunto subscribe Imy name this 6th day of April, 1926.

ROBERT F. BRACKE. 

